First Strike removed off my PS3?

Well I was playing zombies Ascension yesterday...today I try to play it, it tells me I don't have it anymore, and wants me to purchase first strike wtf? I downloaded the First Strike off my friends account, is psn going through ppls systems to get rid of who haven't purchased it or what's going on? I'm re-downloading the First Strike atm, since I want to play some more zombies :D Any real helpful info would be a plus...Thank You in advance!